Percolation across households in mechanistic models of non-pharmaceutical interventions in SARS-CoV-2 disease dynamics.

Since the emergence of the novel coronavirus disease 2019 (COVID-19), mathematical modelling has become an important tool for planning strategies to combat the pandemic by supporting decision-making and public policies, as well as allowing an assessment of the effect of different intervention scenarios. A proliferation of compartmental models were developed by the mathematical modelling community in order to understand and make predictions about the spread of COVID-19. While compartmental models are suitable for simulating large populations, the underlying assumption of a well-mixed population might be problematic when considering non-pharmaceutical interventions (NPIs) which have a major impact on the connectivity between individuals in a population. Here we propose a modification to an extended age-structured SEIR (susceptible-exposed-infected-recovered) framework, with dynamic transmission modelled using contact matrices for various settings in Brazil. By assuming that the mitigation strategies for COVID-19 affect the connections among different households, network percolation theory predicts that the connectivity among all households decreases drastically above a certain threshold of removed connections. We incorporated this emergent effect at population level by modulating home contact matrices through a percolation correction function, with the few additional parameters fitted to hospitalisation and mortality data from the city of São Paulo. Our model with percolation effects was better supported by the data than the same model without such effects. By allowing a more reliable assessment of the impact of NPIs, our improved model provides a better description of the epidemiological dynamics and, consequently, better policy recommendations.

International risk of yellow fever spread from the ongoing outbreak in Brazil, December 2016 to May 2017.

States in south-eastern Brazil were recently affected by the largest Yellow Fever (YF) outbreak seen in a decade in Latin America. Here we provide a quantitative assessment of the risk of travel-related international spread of YF indicating that the United States, Argentina, Uruguay, Spain, Italy and Germany may have received at least one travel-related YF case capable of seeding local transmission. Mitigating the risk of imported YF cases seeding local transmission requires heightened surveillance globally.

Polimorfismo CYP1A1*2A e infertilidad en hombres de la región Caribe colombiana / CYP1A1*2A polymorphism and infertility in Colombian Caribbean male subjects

Objetivo: El objetivo de este estudio fue investigar la asociación del polimorfismo CYP1A1*2A (T-C) y la infertilidad en una muestra de hombres del Caribe colombiano. Materiales y Métodos: Se analizaron características macroscópicas y microscópicas de la muestra seminal de 31 hombres infértiles y 20 fértiles. La genotipificación del polimorfismo se realizó a partir de la técnica PCR-RFLP. Resultados: Se encontraron diferencias significativas (p<0.05) en las características seminales microscópicas en ambos grupos. Además, se identificaron alteraciones en movilidad, concentración y/o morfología. Fueron identificados tres genotipos: TT, TC y CC. En los inértiles se presentaron 25 individuos con genotipo TT (80.6 %), 5 TC (16.1 %) y 1 CC (3.2 %), y en el grupo fértil 16 individuos presentaron genotipo TT (80.0 %), 4 TC (20.0 %) y 0 CC (0.0 %). La distribución genotípica se encontró en equilibrio Hardy - Weinberg en ambos grupos. El análisis de regresión logística mostró que no hubo asociación significativa entre el polimorfismo CYP1A1*2A y la infertilidad en hombres del Caribe colombiano (p>0.05). Conclusión: Estos resultados preliminares sugieren que el polimorfismo CYP1A1*2A no contribuye a la infertilidad masculina en hombres del Caribe colombiano. Sin embargo, son de gran importancia debido a que existe escasa información que asocie polimorfismos del gen CYP1A1 con la infertilidad masculina.

Objective: The aim of this study was to investigate the association of CYP1A1*2A polymorphism (T-C substitution) with male infertility in Colombian Caribbean subjects. Materials and Methods: Macroscopic and microscopic characteristics were analyzed in the semen sample of 31 infertile and 20 fertile men. The polymorphism was genotyped through PCR-RFLP. Results: Both groups evidenced significant differences in microscopic characteristics (p< 0.05), as well as alterations in sperm motility, count and morphology. Three genotypes were identified: wild type homozygous (TT), heterozygous (TC) and variant homozygous (CC). 25 TT genotype (80.6%), 5 TC genotype (16.1%) and 1 CC genotype (3.2%) in infertile men, and 16 TT genotype (80.0%), 4 TC genotype (20.0%) and 0 CC genotype (0.0%) in fertile men were identified. In both infertile and fertile men, distributions of the genotypes were in Hardy-Weinberg equilibrium. Logistic regression analysis showed no significant association between CYP1A1*2A polymorphism and male infertility in Colombian Caribbean men (p>0.05). Conclusion: These preliminary results suggest that CYP1A1*2A polymorphism do not contribute to male infertility of Colombian Caribbean men. However, they are very important because there is limited information about CYP1A1 gene polymorphisms associated with male infertility.

Procesos embrionarios y malformaciones congénitas. Revisión con reporte de casos / Embryonic processes and congenital malformations. Review with case reports

Los procesos fundamentales de la dinámica embrionaria en el reino animal, y particularmente en los vertebrados, obedecen a un programa genético que solo ha comenzado a comprenderse en los últimos años. Uno de los principales objetivos de los biólogos del desarrollo es develar el misterio de cómo un oocito, después de ser fecundado, se transforma en un organismo multicelular. Esta dinámica requiere la activación de un complejo programa de desarrollo en el que genes específicos se expresan en una secuencia temporal precisa, y en la ubicación correcta, para dar origen a diferentes tipos de tejidos como la piel, músculos y nervios, entre otros. Mediante el estudio de mutantes en Drosophila se han identificado genes que participan en la organización del patrón de desarrollo del embrión, los cuales son activos en las hembras. Asimismo, en los últimos años, gracias a las técnicas moleculares, se han realizado grandes avances en el conocimiento de los mecanismos que controlan este intrincado proceso. Este trabajo plantea diversos aspectos relacionados con la teratogenia asociada a la gastrulación, periodo que es muy sensible a las agresiones, así como el aporte de casos y un análisis de los avances en el conocimiento de los procesos moleculares implicados en la dinámica embrionaria.

The fundamental processes of embryonic dynamics in the animal kingdom and particularly in vertebrates are due to a genetic program that has begun to be understood in recent years. One of the developmental biologists' main goals is to unravel the mystery of how after being fertilized an oocyte becomes a multicellular organism. This dynamic requires activation of a complex development program in which genes are expressed in a temporal, precise sequence and in the correct location to give rise to different types of tissues such as skin, muscles and nerves among others. The genes involved in the embryo development pattern, active in females, have been identified by studying Drosophila mutants. Also, thanks to molecular techniques, advances in understanding the intricate mechanism that control this process have been significant in recent years. This work raises several issues related to teratogenicity associated with gastrulation, embryonic stage sensitive to damages. Also, this work provides study cases and a review of the progress in the understanding of molecular processes involved in embryonic dynamics.